I missed the use of quadruple innies and outies in this puzzle. This puzzle was fairly easy. Just the end was interesting. It needed some thought. First time i implemented a xyz-wing in a Killer Sudoku. But i can be by-passed. Just looks fun.Ruud wrote:Ever heard of quadruple innies and outies? If you want to practice this technique, use this week's Assassin.
1. R12C5 = {16/25/34}: no 7,8,9
2. R1C678 = {389/479/569/578}: no 1,2
3. R2C123 = {489/579/678}: no 1,2,3
4. R23C4 = {17/26/35}: no 4,8,9
5. 12(4) in R3C1 = {1236/1245}: no 7,8,9; 1,2 locked in 12(4) -->> R1C2: no 1,2
6. R3C56 = {39/48/57}: no 1,2,6
7. R7C45 = {49/58/67}: no 1,2,3
8. R78C6 = {15/24}: no 3,6,7,8,9
9. R89C5 = {59/68}: no 1,2,3,4,7
10. R9C234 = {289/379/469/478/568}: no 1
11. 45 on R1: 2 innies: R1C59 = 7 = {16/25/34}: no 7,8,9
12. 45 on N1: 2 outies: R1C4 + R4C2 = 6 = {15/24/33}: no 6,7,8,9
13. 45 on R9: 2 innies: R9C15 = 6 = [15]
13a. R8C5 = 9
13b. R7C45 = {67}: locked for R7 and N8
13c. R78C6 = {24}: locked for C6 and N8
13d. Naked Pair: R9C46 = {38}; locked for R9 and N8
13e. R8C4 = 1
13f. Clean up: R12C5: no 2; R3C5: no 8; R3C6: no 3, 7; R23C4: no 7
14. 45 on C123 : 2 outies : R19C4 = 10 = [28]
14a. R9C6 = 3; R4C2 = 4 (step 12)
14b. 12(4) in R3C1 = {125}4: R3C123 = {125} -->> locked for R3 and N1
14c. 8(2) in R23C4 = [53]; 12(2) in R3C56 = [48]
14d. R12C5 = {16} -->> locked for C5 and N2
14e. R7C45 = [67]
14f. Naked Triple {679} in R3C789: locked for N3
14g. Naked pair {79} in R12C6-->> locked for C6
15. 45 on N9: 1 outie: R6C8 = 4
16. 20(3) in R1C6 = {389/578}: no {479} can’t have both {79} -->> R1C7: no 4; 8 locked in R1C78 for R1 and N3
17. 18(4) in R1C1 = {349/367}2 -->> 3 locked in 18(4) for R1
17a. 20(3) = [7]{58}; R2C6 = 9
17b. R1C78 = {58}: locked for N3
17c. 18(4) in R1C1 = {349}2 : R1C123 = {349} locked for R1 and N1
17d. R1C9 = 1; R12C5 = [61]
18. 17(4) in R1C9 = 1{349}: no 1{367} because it needs 2 of {234} in R2C89
18a. R2C89 = [34]; R3C8 = 9; R2C7 = 2
19. 24(4) in R2C6 = 92{67}: needs one of {67} in R3C7
19a. Naked Pair {67}in R34C7: locked for C7
20. R5C4 = 4(hidden, that must have been there for ages)
21. 19(3) in R9C2 = {{29}/[74]}8: no 6
21a. 6 locked in N7 for R8
21b. 13(3) in R8C7 = {238/247}-->> 2 locked for R8 and N9; 13(3): no 5
21c. R78C6 = [24]
21d. 13(3) in R8C7 = {238} -->> locked for R8 and N9
21e. 20(4) in R9C6 = 3[4]{67}; locked for R9; (R9C7 = 4)
21f. Naked Triple {159} in R7C789 -->> locked for R7
22. 22(4) in R7C2 = [8]{67}1 -->> locked for N7 (R7C2 = 8)
22a. R8C3 = 5
22b. Naked Pair {67} in R28C2 -->> locked for C2
22c. Naked Pair {67} in R39C9 -->> locked for C9
23. 15(4) in R6C3 = [63]51 (R67C3 = [63])
23a. R7C1 = 4; R1C3 = 4(hidden)
23b. 16(4) in R4C1 = {237}4 -->> R456C1 = {237} locked for C1 and N4
23c. R1C12 = [93]; R3C1 = 5; R8C12 = [67]; R2C123 = [867]
24. 13(3) in R5C4 = 4[36/81]: no 2,5
25. 21(4) in R3C9 = {2379/2568}: no {3567} because only room for 1 of {67} -->> 2 locked in R456C9 for C9 and N6
25a. R8C8 = 2(hidden)
26. 16(3) in R6C4 = [781/925]: {358} clashes with R5C5 -->> no 3
26a.16(3) in R4C4 = [781/925]: {358} clashes with R5C5, {169} clashes with R5C6, {268} doesn’t have 7 or 9 in R4C4, {367} clashes with R4C7 -->> no 3,6
26b. R5C5 = 3, R5C6 = 6(both hidden in N5)
27. 20(4) in R4C8 = {1379/1568}
27a. Only place for 6 is R4C8: no 5, 8
27b. Only place for 3 is R6C7: no 9
28. 16(3) in R4C4 = [925]: [781] clashes with R4C78
28a. R6C456 = [781]
28b. Naked Triple {358} in R168C7 -->> locked for C7
29. XYZ-wing in R5C27 + R6C2 -->> R5C3: no 9
29a. Naked Pair {18} in R45C3 -->> locked for C3 and N4
29b. R3C23 = [12]; R9C23 = [29]
30. R4C79 needs at least one of {68} because of R4C1
30a. 20(4) in R4C8 = {1379}: {1568} clashes with step 30 -->> locked for N6
30b. R4C7 = 6; R4C9 = 8; R3C79 = [76]; R45C3 = [18]; R4C8 = 7; R456C1 = [372]
30c. R56C9 = [25]; R56C2 = [59]; R5C78 = [91]; R6C7 = 3; R7C789 = [159]
30d. R8C79 = [83]; R9C89 = [67]; R1C78 = [58]
And we are done.
greetings
Para